Chris Bray and his father, Kenneth, attended the launch of STS-135, the final space shuttle mission, on July 8. Thirty years earlier, they saw the launch of STS-1, the very first one. Possessing nearly identical photos of himself and his father at the two launches, Bray uploaded a composite image of them to Flickr and posted a link to the image on Reddit. It quickly shot up the ranks.

It has been viewed on Flickr more than 700,000 times and has garnered media coverage by the likes of Washington Post and MSNBC. [See the image.]

Here is the story behind the two photos.

Chris Bray was 13 in 1981, when the first photo was taken. His father, who was 39, is seen peering through binoculars aimed at the launch site. Both had an avid interest in astronomy and the space program and were thrilled to be in Florida for STS-1. [FAQ: The Maiden Voyage of the Space Shuttle]

Flash forward thirty years to the present: Chris, now the technical director at an interactive marketing agency in New York, and a musician, won tickets to the final shuttle launch in a ticket lottery. "When we finally procured tickets to STS-135, I thought it would be fun to take a similar photo since we had always loved the original," he told Life's Little Mysteries, a sister site to SPACE.com. "We weren't out to replicate it exactly. We just wanted a similar photo to mark the occasion." His girlfriend took that photo.

After Bray shared the composite Flickr image on Reddit, the public reaction was almost instantaneous — and tremendous. "We are humbled by the response and happy that we could share it with everyone," he wrote in an email.

As he understands it, there are three elements that account for the attention the image has received. "The nostalgia, the historical context, and the sentimental father/son personal connection: These three elements together seemed to have struck a chord," he wrote.